Red River Gorge, KY

Wednesday, September 24, 2014

Invasives and Natives - Emerald Ash Borer and Blue Ash

Last week I posted an introduction to the emerald ash borer (EAB: Agrilus planipennis), an exotic invasive wood-boring beetle that since 2002 has been spreading throughout the landscape of the eastern United States and Canada. As the name implies, EAB targets ash trees (genus Fraxinus) and infestations can lead to tree mortality very quickly.

Ash trees are important components of urban and suburban ecosystems, as they are very popular street trees. In central Kentucky, however, one species of ash represents much more than the ash trees used for ornamental landscaping. Blue ash (Fraxinus quadrangulata) is a major component of woodlands in the Bluegrass region. These large, impressive trees have narrow range restrictions, and are most often found in association with limestone-based soils, such as those found in the Bluegrass. This species, along with chinquapin oak (Quercus muehlenbergii), is indicative of an anomalous (and controversial!) vegetative community, the Bluegrass savanna-woodland. (Note: I hope to spend some time discussing that controversy sometime soon! Was the Inner Bluegrass made up of savanna-woodlands with sparse tree canopy cover and understories comprised of cane and clover? The answer is tricky, and none too clear!)

Regardless of the precise pre-European vegetative composition of the Inner Bluegrass, these large, ancient (many date to the late 1600's/early 1700's!) blue ash trees are irreplaceable components of Kentucky's native biota. The emerald ash borer represents a dire challenge to the fitness of these stately trees, and a threat to overall biodiversity. What can you do to help? Next time, I plan to discuss ways in which interested naturalists and citizen scientists can play a huge role in the fight to preserve native ash trees and monitor the spread of EAB.

We are starting to discuss plants in more detail in BIO 1164: Biology and Human Concerns. On Thursday, 9/25/2014 we'll have lab outside, and we'll begin learning to identify some trees common to our region. There are many examples of native trees on campus at Transylvania University, so we'll have plenty of specimens to practice with! Beyond learning some tree ID skills, I hope that my students will become familiar with the ins and outs of using dichotomous keys. That's an important skill for any naturalist to have, one that will make identifying other groups such as birds or insects much easier for them!